Exhaust gas after-treatment device for vehicle engine

ABSTRACT

An exhaust gas after-treatment device for an engine comprises a first catalyst configured to decrease an amount of a hydrocarbon contained in an exhaust gas; and a second catalyst disposed in sequence with the first catalyst, the second catalyst configured to reduce an amount of a nitrogen oxide contained in the exhaust gas, wherein the exhaust gas after-treatment device is disposed on an exhaust passage of the engine and the second catalyst is prepared by engine bench aging.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to Korean Patent Application No. 10-2014-0175832, filed in the Korean Intellectual Property Office on Dec. 9, 2014, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an exhaust gas after-treatment device for a vehicle engine. More particularly, the present disclosure relates to an exhaust gas after-treatment device for a vehicle engine having a catalyst prepared using an engine bench aging process.

BACKGROUND

In general, an exhaust gas after-treatment device functions to remove or reduce emissions from the exhaust gas.

Currently, in order to prevent global warming and to protect the atmospheric environment, regulations on vehicle exhaust gas are tightening. In particular, regulations on nitrogen oxide (NO_(x)), particulate matter (PM), greenhouse gases (such as CO₂), and other exhaust gases are tightening, and OBD (On-Board Diagnostics) regulations that monitor the performance of the exhaust gas processing are also tightening. That is, it is essential to meet exhaust gas regulations in a state where a vehicle system is operating normally, and it is also required to meet OBD regulations even in a state where a component involved in processing vehicle exhaust gas is out of order.

If the emission contained in the exhaust gas exceeds an OBD regulation value, a warning lamp (MIL) may be lighted to induce component maintenance. As the regulations on vehicle exhaust gas are tightened with EURO-5/6, meeting the OBD regulations becomes difficult with conventional combustion technologies, even though it was possible to comply with the regulations of EURO-4 and before EURO-4 with such conventional technologies. Consequently, in order to meet the OBD regulations of the EURO-5/6, manufacturers are considering mounting an additional exhaust gas after-treatment device.

The OBD regulations of the EURO-5 provide for 0.54 g/km of nitrogen oxide (NO_(x)) as a maximum emission value, and not to exceed 0.648 g/km which is 120% of the maximum value in a case where a component related to the exhaust gas is out of order. In the meantime, the OBD regulations of the EURO-6 are tightened further to permit nitrogen oxide (NO_(x)) only up to 0.4 g/kWh which is 1/5 of EURO-5 in a case of a large diesel vehicle.

In order to meet the OBD regulations of the EURO-5/6, it may be necessary to add a separate catalyst device to the exhaust gas after-treatment device. If the separate catalyst device is thus added, weight and cost of the exhaust gas after-treatment device may increase and fuel consumption of the engine may resultantly increase.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

SUMMARY

The present disclosure has been made in an effort to provide an exhaust gas after-treatment device for a vehicle engine, the disclosure providing advantages relating to meeting tightened environmental regulations without needing further additional elements.

Accordingly, an aspect of the present disclosure related to solving the above problems provides an exhaust gas after-treatment device for a vehicle engine which may meet tightened environmental regulations without the addition of any element.

To achieve one aspect of the present disclosure, an exhaust gas after-treatment device for an engine comprises a first catalyst configured to decrease an amount of a hydrocarbon contained in an exhaust gas; and a second catalyst disposed in sequence with the first catalyst, the second catalyst configured to reduce an amount of a nitrogen oxide contained in the exhaust gas, wherein the exhaust gas after-treatment device is disposed on an exhaust passage of the engine and the second catalyst is prepared by engine bench aging.

The first catalyst may be prepared by aging in an electric furnace.

The first catalyst may be a palladium catalyst.

The second catalyst may be a rhodium catalyst.

The first catalyst may be aged for a preset time period at a temperature of 1250° C.

The first catalyst may be aged for between 25 and 150 hours.

The first catalyst may be aged for a preset time period at a temperature between 1000° C. and 1100° C. and the electric furnace may further comprise nitrogen.

When the first catalyst is aged at a temperature between 1000° C. and 1100° C. and the electric furnace further comprises nitrogen, the first catalyst may be aged for between 25 and 100 hours.

The second catalyst may be aged by engine bench aging for a preset time period with an air/fuel ratio of lambda 0.95 to 1.1 and a temperature of 1000° C. to 1100° C.

The second catalyst may be aged for between 25 and 100 hours.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic view of an OBD system having an exhaust gas after-treatment device for a vehicle engine in accordance with an exemplary embodiment of the present inventive concept applied thereto.

FIG. 2 illustrates a schematic view of an exhaust gas after-treatment device for a vehicle engine in accordance with an exemplary embodiment of the present inventive concept.

DETAILED DESCRIPTION

An exemplary embodiment of the present inventive concept will hereinafter be described in detail with reference to the accompanying drawings.

FIG. 1 illustrates a schematic view of an OBD system having an exhaust gas after-treatment device for a vehicle engine in accordance with an exemplary embodiment of the present inventive concept applied thereto.

As shown in FIG. 1, the OBD system includes an engine 10, a fuel tank 20, a sensing unit 30, a purge control sensor 40, an after-treatment device 50 and an oxygen sensor 60.

The sensing unit 30 is a device connected to the engine 10 and the fuel tank 20 for sensing misfire of the engine and evaporation of the fuel. The purge control sensor 40 is provided for performing sensing of evaporation gas to control evaporation gas moving from a canister to a carburetor or a surge tank. Since the fuel tank 20, the sensing unit 30, and the purge control sensor 40 are well known to a person of ordinary skill in the art, detailed description of these components will be omitted.

The after-treatment device 50 is arranged on an exhaust gas passage of the engine 10 for carrying out after-treatment of the exhaust gas.

The oxygen sensor 60 is provided for measuring a content of oxygen in the exhaust gas. The oxygen sensor 60 has a first oxygen sensor 62 arranged in front of the after-treatment device 50 on the exhaust passage of the engine 10 and a second oxygen sensor 64 disposed in sequence after the after-treatment device 50 on exhaust passage of the engine 10. Moreover, by comparing the oxygen content of the exhaust gas measured with the first oxygen sensor 62 to the oxygen content of the exhaust gas measured with the second oxygen sensor 64, an exhaust gas after treatment performance of the after-treatment device 50 may be diagnosed.

FIG. 2 illustrates a schematic view of an exhaust gas after-treatment device in an engine in accordance with an exemplary embodiment of the present inventive concept.

As shown in FIG. 2, the after-treatment device 50 in an engine includes a front catalyst 52 and a rear catalyst 54.

The front catalyst 52 is a catalyst for reducing the amount of hydrocarbon in the exhaust gas. In one embodiment of the present inventive concept, the front catalyst 52 is predominantly a palladium catalyst. Moreover, the front catalyst 52 may be prepared by aging in an electric furnace. The aging in the electric furnace may progress for about 25 to 150 hours at a temperature of 1250° C. If nitrogen is introduced to the electric furnace, the aging may progress for about 25 to 100 hours at a temperature of 1000° C. to 1100° C. As such electric furnace aging is well known to a person of ordinary skill in the art, no more detailed description regarding these components will be provided.

The rear catalyst 54 is a catalyst for reducing the amount of nitrogen oxide (NO_(x)) contained in the exhaust gas and it is disposed in sequence after the front catalyst 52 on the exhaust gas passage. The rear catalyst 54 may be predominantly a rhodium catalyst. The rear catalyst 54 may be prepared by engine bench aging. The engine bench aging may progress for about 25 to 100 hours in a condition of an air/fuel ratio of lambda 0.95 to 1.1, and a temperature of 1000° C. to 1100° C.

If the rear catalyst 54 is aged in the engine bench aging condition, aging of the rhodium Rh in the rear catalyst 54 may be maximally suppressed. Under these conditions, a performance of the rear catalyst 54 may be improved. If the performance of the rear catalyst 54 is thus improved, the heightened environment regulations may be met while no additional catalyst device may be required for reducing the amount of nitrogen oxide (NO_(x)) in the vehicle emissions.

The engine bench aging of the rear catalyst may be performed by different methods depending on a choice of design by a person of ordinary skill in the art.

Thus, according to an exemplary embodiment of the present inventive concept, the aging of the catalyst by using the engine bench allows one to enhance a performance of an exhaust gas after-treatment device for a vehicle engine without addition of any additional element. Thus, unnecessary increases in cost and weight may be avoided. Moreover, fuel consumption of the engine may be improved.

While this inventive concept has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the inventive concept is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

What is claimed is:
 1. An exhaust gas after-treatment device for an engine comprising: a first catalyst configured to decrease an amount of a hydrocarbon contained in an exhaust gas; and a second catalyst disposed in sequence with the first catalyst, the second catalyst configured to reduce an amount of a nitrogen oxide contained in the exhaust gas, wherein the exhaust gas after-treatment device is disposed on an exhaust passage of the engine and the second catalyst is prepared by engine bench aging.
 2. The exhaust gas after-treatment device of claim 1, wherein the first catalyst is prepared by aging in an electric furnace.
 3. The exhaust gas after-treatment device of claim 1, wherein the first catalyst is a palladium catalyst.
 4. The exhaust gas after-treatment device of claim 1, wherein the second catalyst is a rhodium catalyst.
 5. The exhaust gas after-treatment device of claim 2, wherein the first catalyst is aged for a preset time period at a temperature of 1250° C.
 6. The exhaust gas after-treatment device of claim 5, wherein the preset time period is between 25 and 150 hours.
 7. The exhaust gas after-treatment device of claim 2, wherein the first catalyst is aged for a preset time period at a temperature between 1000° C. and 1100° C. and the electric furnace further comprises nitrogen.
 8. The exhaust gas after-treatment device of claim 7, wherein the preset time period is between 25 and 100 hours.
 9. The exhaust gas after-treatment device of claim 1, wherein the second catalyst is aged by engine bench aging for a preset time period with an air/fuel ratio of lambda 0.95 to 1.1 and a temperature of 1000° C. to 1100° C.
 10. The exhaust gas after-treatment device of claim 9, wherein the preset time period is between 25 and 100 hours. 